The invention relates to transgenic cells and animals having an Ikaros transgene and methods, e.g., drug screening, or immunological assay methods, using such cells or animals.
The generation of the T cell repertoire from a progenitor stem cell proceeds through a differentiation pathway in which the later intrathymic steps are well documented while the early extrathymic events are only poorly characterized. One of the earliest definitive T cell differentiation markers is the CD3.delta. gene of the CD3/TCR complex.